The subject invention falls generally in the field of lawn mowers or other devices in which rotating blades are used to cut vegetable material, such as grass, weeds, small tress, bushes and the like. The invention is primarily adapted as a cutting blade assembly component for such described apparatus. In general, however, the invention's application falls mostly into the lawn mower category.
Lawn mower assemblies have evolved from the early stages of being simplistic, manually operated devices, with the rotor being driven about an axis which is parallel to the ground and perpendicular to the mower's path of travel. Such earlier versions of lawn mowers were manually driven devices, and the early types of motor driven mowers were based around this latter type of rotor apparatus. Later lawn mowers, with electrically driven or gasoline driven engines, evolved, for the greater part, to assemblies in which the driven shaft is disposed vertically downward beneath the lawn mower assembly with the rotor and blade members being rotated about a vertically downward axis; with the blades being driven through a path which is substantially parallel to the ground level. In this latter type of power mower apparatus, there usually is a metallic blade assembly, in turn comprised in part of a multiple-bladed metallic rotor. This rotor, with attached blades, usually moves in a rotational path which encompasses almost the entire area beneath the mower assembly during the cutting operation. In this assembly, with the rotatable metallic blades, the moving blades, while rotating under the housing assembly, present several safety hazards and operational problems.
In this latter regard, one of the most prevalent safety problems is the potential danger of injury to the user's or a bystander's feet by the mower blades, if foot contact is accidently made with the whirling blades while they are being rotated by the mower engine. Other dangers inherent in the usage of metallic blades include situations whereby the revolving metallic blades strike a free standing object, such as a rock, and propel the object from under the mower assembly in a transverse, and partially upward direction. Such a thrown projectile poses obvious problems to bystanders of all ages and sizes, since rotating metallic blades can impart, by a substantial centrifugal force effect, a substantial amount of momentum to the propelled object. This latter safety hazard is omnipresent concern with powered lawn mowers using such metallic blades.
Other similarly generated safety hazards are frequently incurred in the use of such revolving metallic blades in a power lawn mower apparatus.
There are even other disadvantages with the use of metallic mower blades on power lawn mowers, such as the potential problem that frequently occurs when the rotating blades strike a fixed hardened object, such as a rock impacted in the ground or a stump. Often such moving impact by the rotating blades can result in blade or other mower damage, leading to further operational problems. The resultant blade damage can render a power lawn mower virtually ineffective. This problem is most acute when metallic blade assemblies are used.
There have been a limited number of lawn mower blade assemblies, and similar weed cutting machines, which have been adapted to incorporate non-metallic blades as cutting mechanisms. More specifically, a limited array of lawn mower assemblies have incorporated lawn mower blades comprised of a non-metallic material. U.S. Pat. Nos. 4,065,913; 4,126,990 and 4,062,114 represent limited examples of such types of non-metallic blade lawn mower blade assemblies.
There are several problems found to exist with the operation, usage, and maintenance of such known flexible, non-metallic lawn mower blade assemblies. Once such difficulty is centered around the fact that in the existing art of non-metallic bladed devices the individual blades are usually, in general, inefficient in cutting grass and weeds by reason of the various shortcomings in the blade composition, shape, installation and integrated assembly to promote effective cutting. Problems also exist in the fact that many such prior art blade structures are not capable, by reason of their relative flaccid structure and composition, to project rigidly erect and taut in a radially outwardly, horizontal position as the blades revolve in circular sweeping fashion about the central vertically disposed drive axis. What occurs is that said prior art blades, being relatively non-rigid and flaccid, do not achieve the most optimal horizontal position and rigidity upon impartation of centrifugal rotative force. In these circumstances, where the blades do not achieve this optimal horizontally and radially extended taut position, their respective, individual cutting surfaces do not achieve their maximal cutting effectiveness.
This invention is thus directed to a solution of the foregoing problems cited in the existing art, and the following objects of the subject invention are directed accordingly to this end.